Spin dynamics and magnetic field induced polarization of excitons in ultrathin GaAs/AlAs quantum wells with indirect band gap and type-II band alignment

The exciton spin dynamics are investigated both experimentally and theoretically in two-monolayer-thick GaAs/AlAs quantum wells with an indirect band gap and a type-II band alignment. The magnetic field induced circular polarization of photoluminescence Pc is studied as function of the magnetic fiel...

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Bibliographic Details
Published in:Physical review. B 2017-07, Vol.96 (3), Article 035302
Main Authors: Shamirzaev, T. S., Rautert, J., Yakovlev, D. R., Debus, J., Gornov, A. Yu, Glazov, M. M., Ivchenko, E. L., Bayer, M.
Format: Article
Language:English
Subjects:
Alignment
Aluminum arsenides
Band gap
Circular polarization
Electron spin
Energy gap
Excitons
Field strength
Gallium arsenide
Induced polarization
Magnetic fields
Photoluminescence
Quantum wells
Spin dynamics
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Summary:The exciton spin dynamics are investigated both experimentally and theoretically in two-monolayer-thick GaAs/AlAs quantum wells with an indirect band gap and a type-II band alignment. The magnetic field induced circular polarization of photoluminescence Pc is studied as function of the magnetic field strength and direction as well as sample temperature. The observed nonmonotonic behavior of these functions is provided by the interplay of bright and dark exciton states contributing to the emission. To interpret the experiment, we have developed a kinetic master equation model which accounts for the dynamics of the spin states in this exciton quartet, radiative and nonradiative recombination processes, and redistribution of excitons between these states as result of spin relaxation. The model offers quantitative agreement with experiment and allows us to evaluate, for the studied structure, the heavy-hole g factor, ghh=+3.5, and the spin relaxation times of electron, τse=33μs, and hole, τsh=3μs, bound in the exciton.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.96.035302